AN ANALYSIS OF CATCH AND EFFORT DATA FROM THE U.S. 



RECREATIONAL FISHERY FOR BILLFISHES (ISTIOPHORIDAE) IN THE 



WESTERN NORTH ATLANTIC OCEAN AND GULF OF MEXICO, I971-78» 



Grant L. Beardsley and Ramon J. Conser^ 



ABSTRACT 



Catch and effort data from the United States recreational fishery for billfishes in the Atlantic Ocean 

 and Gulf of Mexico were examined to evaluate their usefulness in determining trends in abundance. In 

 the Gulf of Mexico, data were recorded from both organized fishing tournaments and from non- 

 competitive fishing. A fishing power model was developed and comparisons made between catch per 

 unit effort from tournament data, nontoumament data, and Japanese longline data. The results 

 indicate that catch and effort statistics for white marlin, Tetrapturus albidus, and sailfish, Istiophorus 

 platypterus, in the Gulf of Mexico appear to be reliable and can be aggregated to provide a means of 

 indexing relative abundance of these species. The model did not appear to be appropriate for blue 

 marlin, Makaira nigricans, however The general trend in catch per unit effort from 1972 to 1978 for 

 sailfish and white marlin in the Gulf of Mexico appears to be downward. 



Based on catch per unit effort from all fishing areas, there appears to be a single stock of white marlin 

 in the western North Atlantic and Gulf of Mexico. 



In 1971, the National Marine Fisheries Service's 

 Southeast Fisheries Center initiated research on 

 the billfish stocks of the western North Atlantic 

 Ocean and Gulf of Mexico. The purpose of this 

 research was to develop and evaluate a method of 

 determining changes in relative abundance of bill- 

 fish stocks using catch and effort data from the 

 recreational fishery. This report has been prepared 

 to present a description of this research, evaluate 

 the reliability of the sampling techniques, and 

 make a preliminary determination of the validity 

 of catch and effort data from the recreational 

 fishery as an indicator of changes in relative 

 abundance of billfish populations. 



THE RECREATIONAL FISHERY 



The development of the U.S. recreational 

 fishery for billfishes (families Istiophoridae and 

 Xiphiidae) has been reviewed in detail by de Sylva 

 (1974). The first sailfish caught by rod and reel in 

 the Atlantic was probably taken off Miami, Fla., 

 around the turn of the century. After World War 11, 

 increased leisure time and affluence coupled with 

 newer and better fishing gear, vessels, and angling 

 techniques spurred a dramatic expansion of the 



'Southeast Fisheries Center Contribution No. 81-20M. 



^Southeast Fisheries Center Miami Laboratory, National 

 Marine Fisheries Service, NOAA, 75 Virginia Beach Drive, 

 Miami, FL 33149. 



Manuscript accepted August 1980. 

 FISHERY BULLETIN: VOL. 79, NO. 1, 1981. 



fishery geographically as well as to a broader seg- 

 ment of the population. In the Atlantic, anglers 

 now fish for billfishes from almost every state 

 along the eastern coast of the United States as well 

 as from the U.S. Virgin Islands, Puerto Rico, and 

 numerous foreign ports. 



Species 



The billfish species in the Atlantic recreational 

 fishery are the sailfish, Istiophorus platypterus, 

 the white marlin, Tetrapturus albidus, the blue 

 marlin, Makaira nigricans, and to a much lesser 

 extent the swordfish, Xiphias gladius, and the 

 longbill spearfish, Tetrapturus pfluegeri. Sailfish, 

 the most commonly occurring species in the catch, 

 is more coastal in its habitat than any of the other 

 species and consequently is available to a greater 

 number of anglers. It is also the smallest in aver- 

 age size, with the possible exception of the longbill 

 spearfish, and generally requires less expensive 

 and sophisticated fishing tackle than is commonly 

 used in fishing for marlins. The two marlins are 

 most abundant in oceanic waters, generally far 

 from the coast of the United States, and fishing for 

 marlins usually requires relatively large vessels 

 and expensive fishing gear. Prior to 1976, recre- 

 ational fishing for swordfish was a specialized type 

 of fishing where the fish was usually sighted be- 

 fore the fishing lines were placed in the water. 



49 



